RICE RATS 279 



Characters. — Size very large ; ears medium or rather small ; hind 

 feet and tail long; color pale fulvous; skull unique : large, massive; 

 with greatly swollen and strongly decurved rostrum. 



Color. — Upperparts ochraceous or buffy fulvous, most intense on 

 rump, becoming buffy grayish anteriorly, especially on face ; under- 

 parts white, the slaty underfur showing through ; tail brown, paler 

 below. Ears brown ; feet whitish. 



Cranial characters. — Skull large, massive, somewhat flattened 

 above, with strongly marked and nearly straight superciliary beads, 

 rather heavy zygomata, bowed outward in middle ; acute decurved 

 nasals, ending essentially on plane of premaxillae ; enormously swol- 

 len and strongly decurved rostrum; moderate palatal slits; rather 

 large molars (not large for size of skull), and large, broad, and 

 shortly curved upper incisors. 



Measuretnents. — Average of 2 adult males from type locality : total 

 length 343 mm.; tail vertebrse 190; hind foot 38.5. An adult 

 female: total length 320; tail vertebrae 185; hind foot 37. 



ORYZOMYS ALBIVENTER sp. nov. 



Type from Ameca, Jalisco, Mexico. No. 82236 $ ad. U. S. 

 National Museum, Biological Survey Coll. February 6, 1897. E. 

 W. Nelson and E. A. Goldman. Original number 10478. 



Characters. — Size large ; ears short ; color light golden fulvous ; 

 underparts ivhite. Skull and teeth large and heavy. 



Color. — Upperparts bright ochraceous, brightest on rump, more 

 grayish anteriorly ; back strongly lined with black hairs ; underparts 

 clear white without buffy or salmon suffusion ; tail bicolor, dusky 

 above, whitish below. 



Cranial characters. — Skull large and heavy ; zygomata rather 

 broadly spreading ; nasals large and broad, slightly exceeding pre- 

 maxillae ; supercilary ridges well developed, nearly straight; in- 

 cisive foramina long, but not so broadly open as in crinitus ; molars 

 larger and heavier than in any other known species, the series 

 measuring over 5 mm. 



Remarks. — The only near relative of albiventer seems to be 

 aquaticus from the lower Rio Grande region in Texas. Externally it 

 resembles aquaticus closely as seen from above, although the rump is 

 more intense fulvous, but the underparts are white, while in aquaticus 

 they are buffy fulvous. The skull differs from aquaticus in having 

 much less pronounced superciliary beads, less marked orbital angle 

 of frontal [frontals less swollen anteriorly] ; larger incisive foramina, 

 and decidedly larger molars. 



